Ecology: Lecture 3

1
Ecology Lecture 3

• Plant adaptations to the light environment
  (Physiological Ecology)

2
PAR Photosynthetically active radiation
(400-740 nm)
3
P-I Curve
4
Photoinhibition
5
Photosynthesis review
6
Photosynthesis light-dependent reactions

• What do these reactions accomplish?

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Photosynthesis light-independent reactions

• What do these reaction accomplish?
• Role of rubisco?

8
Benefit vs. cost of rubisco reduction
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Changes in leaf orientation
10
Shade-tolerant vs. intolerant plants

• Terrestrial
  Aquatic

11
Responses to UV radiation

• What is the relationship between the ozone layer
  and UV-B?
• What are the consequences of UV-B exposure to
  primary producers?
• DNA damage, change in growth form, reduction in
  yield
• Example In situ studies in the Antarctic ozone
  hole (1990) suggest a reduction of 6-12 of
  primary production due to the ozone hole

12
Plant defenses against UV-B

• Compounds that absorb UV-B
• Effects on photosynthesis?
• Tropical and alpine plants are more capable of
  blocking UV-B radiation
• Does this make adaptive sense? How so?
• Plants with short-lived seasonal leaves were less
  effective at blocking UV-B rays.
• Does this make adaptive sense? How so?